1. Field of the Invention
The present invention relates generally to methods for manufacturing belts, and more specifically to methods for manufacturing endless, molded belts in a single process.
2. Description of the Prior Art
Belts are frequently used in a variety of manufacturing processes for driving parts of machinery, including other belts. In order for belts to operate correctly, they must track properly on the pulleys. In paper handling machines, improper belt tracking could cause paper jam-ups. Several methods for guiding belts have been developed. Because of space limitations in machinery, some such methods, including belt-tracking devices are unsatisfactory.
Often, the most desirable method of tracking a flat belt is the use of crowned pulleys. When pulley crowning proves ineffective, molded profiles on the belt for the purpose of tracking can be very effective. However, prior to applicant's invention, there was only one variety of flat, guided belt that was readily available. Unsupported rubber belts do not require a pulley take-up and can be used with a range of molded profiles. However, the unsupported belt has proven unacceptable for any high-tension application, for the reason that such a belt quickly loses its tension when configured in the narrow widths and minimal thicknesses required in many machines. Woven, endless belts do not exhibit the tension-loss that unsupported rubber belts do. However, easily manufactured, woven, endless belts have previously been unavailable with molded profiles for tracking.
Numerous efforts have been made to improve belts for use in machinery. U.S. Pat. No. 4,407,333, issued to Robert A. Fowkes on Oct. 4, 1983, describes a weaving pattern for belting fabric. The patent does not discuss applying synthetic layer to fabric or molding guiding profile into a belt.
U.S. Pat. No. 4,552,620, issued to Richard J. Adams on Nov. 12, 1985, describes a fabric with a sprayed-on urethane coating. The patent does not provide for simultaneous molding of a tracking profile.
U.S. Pat. No. 4,559,258, issued to Masao Kiuchi, on Dec. 17, 1985, describes a fabric with a synthetic coating on both sides. The patent provides for simultaneous molding of drain channels, but does not provide for simultaneous molding of a tracking profile. Additionally, the patent does not suggest the use of an endless sleeve of amorphous, synthetic material outside of a fabric sleeve. Because of this lacking, there is inadequate material in which to mold an effective tracking guide of the nature disclosed in the present invention.
U.S. Pat. No. 4,604,310, issued to Serafino Bertotto, on Aug. 5, 1986, describes a belt comprised by a layer of woven cotton and a layer of woven synthetic material. The two layers are bonded by needling, rather than by heat fusion. There is no teaching of molded tracking profiles.
U.S. Pat. No. 5,171,389, issued to Carl E. Stigberg, on Dec. 15, 1992, describes a method of making a grooved belt by applying a grooved ribbon of synthetic material to a previously manufactured belt comprised by polymeric-resin-impregnated fabric. The patent thus teaches away from the concept of molding tracking profiles in a belt in the same process in which the belt is manufactured.
U.S. Pat. No. 5,238,537, issued to William H. Dutt, on Aug. 24, 1993, describes a belt of a resin-impregnated fabric that can be manufactured to any length because it does not require use of a mandrel. There is no teaching in the patent regarding the molding of tracking profiles in belts.
U.S. Pat. No. 5,277,728, issued to Carl E. Stigberg, on Jan. 11, 1994, describes a polyurethane-coated fabric belt. An additional fibrous material is disposed on the coating. There is no teaching of molding of guide profiles.
U.S. Pat. No. 5,302,251, issued to Christian Schiel, et al., on Apr. 12, 1994, describes a press jacket including a belt with lubricant-retaining grooves. The formation of the grooves results from swelling of longitudinal threads in the belt. There is no teaching of molding of guide profiles.
Japanese Patent 60-88193, issued on Sep. 19, 1983 to Beloit Corp., describes an annular blanket made of woven fabric and coated, as by spraying, with polyurethane. The coating has pores, but there is no teaching of molding guide tracks in the blanket.
None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed.